Opportunity, occasion, chance, break, time are comparable when they mean a state of affairs or a combination of circumstances favorable to some end.
Opportunity is perhaps the most common of these terms; it applies to a situation which provides an opening for doing something, especially in line with one's inclinations, ambitions, purposes, or desires.
Occasion (see also CAUSE 1 ) carries the basic denotation characteristic of its leading senses—a definite moment or juncture, but it applies only to a moment that provides an opportunity or that calls for or prompts action of a definite kind or nature.
Occasion may suggest more strongly than opportunity a juncture that provokes or evokes action.
Chance applies chiefly to an opportunity that comes seemingly by luck or accident. Sometimes the word means little more than a fair or a normal opportunity, especially in negative expressions.
Break applies to the occasion of a stroke of fortune that is usually good unless the term is qualified (as by an adjective indicating the kind of chance or suggesting its outcome).
Time denotes a juncture that is well-timed or opportune (as for the execution of one's end or purpose).